Quasifree electron scattering on atoms in the inverse kinematic system

The measurement of elastic electron scattering is a sensitive tool to test ionic and atomic potentials. Because a dense ionic target is difficult to produce, we use inverse kinematics, i.e. we exchange the roles of projectile and target and transform the cross sections. The absolute singly and doubly differential cross sections for the projectile ionization of He-0 (0.1 MeV/u) scattered by Ne-0, measured for the direct and the inverse system in the whole angular range from 0 degrees to 180 degrees, show the validity of the transformation, We find a pronounced generalized Ramsauer-Townsend minimum in the angular-dependent singly differential cross section, Changing to the Ne3+ target the loss peak is absent in our measurements for larger emission angles. This may be explained by a large capture cross section into bound states of the neon ion, which depends on the impact parameter.